The present invention relates to wireless alarm systems having multiple alarm devices in communication with one or more control units, the control unit containing a system controller, receiver and transmitter; and in particular to such alarm systems where the control unit transmits messages to a wireless user interface device(such as a keypad and display), wireless remote siren and/or wireless remote dialer that indicate an alarm or change of status condition.
A recent innovation in security applications is the use of two-way wireless user interface devices, which are keypads or panic transmitters with system status indicators. These are portable devices, which may be used to control and interrogate the security system for system status. An example of such devices are the 5827BD and 5804BD products available from ADEMCO in Syosset, N.Y. These have the advantages of portability if required, or alternatively may be mounted at an installation, thus reducing the high costs of wiring a conventional wired user interface device. In addition, wireless remote sirens and dialers may be employed to reduce wiring and labor costs.
Typically during alarm system installation, a conventional central control unit is placed into an installation mode and its receiver sensitivity is reduced (see U.S. Pat. No. 4,754,261). This allows the installer to check the transmission signal margin of the alarm devices, i.e. window sensors, door sensors, etc. If the central control unit recognizes an alarm flag from the alarm device at reduced receiver sensitivity, then there will be adequate signal margin during normal operation. That is, if the radio environment changes during normal operation, due to movement of furniture etc., the alarm signals transmitted from the alarm devices have sufficient signal strength to be received by the central control unit receiver in this changed, adverse condition.
In the case where a wireless user interface device with signal receiver capabilities is being installed, ensuring an adequate signal margin between the central control unit transmitter and the wireless user interface device is typically more difficult because the wireless user interface devices currently may not be designed with a keypad selection or a switch to reduce their input sensitivity. It would be advantageous, when the central control unit receiver goes into installation mode (reduced sensitivity), at that same time to place the central control unit transmitter into reduced output power mode, thus obtaining an adequate signal margin in both the up link (user interface device to central control unit receiver) and down link (central control unit transmitter to user interface device).
It is also desirable to ensure that the wireless remote siren and dialer are installed with adequate signal margin so that if the radio environment changes during normal operation, the messages from the central control unit transmitter have sufficient signal strength to be received by the wireless remote device in this changed, adverse condition.
It is therefore an object of the present invention to provide a method for ensuring that an adequate signal margin exists between the central control unit and the wireless devices during an alarm system installation.
It is also an object of the present invention to provide an alarm system that provides means for transmitting between a central control unit and a wireless device at a reduced transmission level during installation mode and at a normal transmission level while not in installation mode.
It is yet a further object of the present invention to provide a common installation mode to verify communication between the central control unit and the wireless alarm devices (window sensors, door sensors, etc.) and at the same time verify communication between the central control unit and the wireless devices having receive capability (user interface devices, remote siren, and remote dialer).